An internal combustion engine that utilizes a duct for transporting exhaust gas from the exhaust system into the intake system, known in the art as exhaust gas recirculation (EGR), generally has a means of controlling the ratio of ambient air to recirculated gas being introduced into the internal combustion engine.
Typically, a throttle valve is used to control the flow of ambient air and a recirculated gas valve is used to control the flow of recirculated gas, wherein the throttle valve and recirculated valve cooperate together to control the ratio of ambient air to recirculated air being introduced into the engine. Under predetermined conditions, the recirculated gas valve is opened to allow recirculated gas to enter the intake system. Under this condition, a first maximum ratio can occur. In order to get increase the ratio of ambient air to recirculated gas, the throttle valve can be closed. Under this condition, a second maximum ratio can occur and will be the maximum ratio having a higher ratio than the first maximum ratio.
It is well known in the art that two separate actuators operate and control the throttle valve and recirculated gas valve independently. This adds costs to the internal combustion engine and requires space for two actuators in an already space constrained internal combustion engine package. However, attempts have been made to try and reduce the cost through the use of a single actuator.
One known apparatus that uses a single actuator for controlling the ambient air to recirculated gas ratio is described in U.S. Pat. No. 6,105,559 issued to Stoltman on Aug. 22, 2000. Stoltman discloses an EGR port and an intake port adjacent to each other and a single rotatable shaft that extends across the two ports and supports an EGR throttle plate and air throttle plate. Because the EGR throttle plate and the throttle plate for fixed to the shaft they both rotate together. This does not allow for a first and a second maximum ratio to occur and the range to ratios is condensed by this action.
Another known apparatus that uses a single actuator for controlling the ambient air to recirculated gas ratio is described in U.S. Pat. No. 4,924,840 issued to Wade on May 15, 1990. Wade discloses an induction passage bifurcated to form an air induction passage and a EGR passage wherein the flow of air and EGR gases are controlled by a pair of butterfly type valves mounted on a common shaft. As would be inherent, and illustrated, the pair of butterfly type valves are separate and located in each one of the air induction passage and EGR passage. As with the same problems with Stoltman, the fixed butterfly valves to the shaft does not allow for a first and a second maximum ratio to occur.
The present disclosure is directed to overcoming one or more of the problems as set forth above.